#define _CRT_SECURE_NO_WARNINGS 1

#include <stdio.h>
#include <assert.h>
#include <string.h>

char* My_strstr(const char* pa, const char* pb)
{
	const char* start1 = NULL;
	const char* start2 = NULL;
	const char* cur = pa;
	if (*pb == '0')
	{
		return (const char*)pb;
	}
	while (*cur)
	{
		start1 = cur;
		start2 = pb;
		while (*start1 && *start2 && *start1 == *start2)
		{
			start1++;
			start2++;
		}
		if (*start2 == '\0')
		{
			return (const char*)cur;
		}
		cur++;
	}
	return NULL;
}

int main()
{
	char str1[20] = "3425588767@qq.com";
	char str2[20] = "@qq.com";
	printf("%s", My_strstr(str1, str2));
	return 0;
}